void printHello(){
  print('hello');
}

String triple(String string){
  return string*3;
}

List every(List<String> list,String f(String str)){
  for(var i=0;i<list.length;i++){
    list[i]=f(list[i]);
  }
  return list;
}

void main(){
  Function f=printHello;
  f();
  List list=[1,2,3,4];
  list.forEach(print);
  List<String> characters=['a','b','c'];
  print(every(characters,triple));
}
